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Title:Photochemistry of (eta(6)-Arene)Cr(CO)(3) (Arene = Methylbenzoate, Naphthalene, or Phenanthrene) in n-Heptane Solution: Population of Two Excited States Following 400 nm Excitation As Detected by Picosecond Time-Resolved Infrared Spectroscopy
Authors:Clark, Ian P. George, Michael W. Greetham, Gregory M. Harvey, Emma C. Long, Conor Manton, Jennifer C. Pryce, Mary T., 2011
Abstract: The photochemistry of (eta(6)-methylbenzoate)Cr(CO)(3), (eta(6)-naphthalene)Cr(CO)(3), and (eta(6)-phenanthrene)Cr(CO)(3) in n-heptane solution was investigated by picosecond time-resolved infrared spectroscopy (TRIR). The observation of two transient IR features in the organic carbonyl region at 1681 and 1724 cm(-1) following 400 nm excitation of (eta(6)-methylbenzoate)Cr(CO)(3) confirms formation of two excited states which are classified as metal-to-arene charge transfer (MACT) and metal-to-CO charge transfer (MCCT), respectively. Time-dependent density functional theory calculations have been used to support these assignments. Population of the MCCT excited state results in a slow (150 ps) expulsion of one CO ligand. Excitation of (eta(6)-naphthalene)Cr(CO)(3) or (eta(6)-phenanthrene)Cr(CO)(3) at either 400 or 345 nm produced two excited states: the MCCT state results in CO loss, while the MACT excited state results in a change to the coordination mode of the polyaromatic ligands before relaxing to the parent complex. A comparison of the infrared absorptions observed following the population of the MACT excited state with those calculated for nonplanar polyaromatic intermediates provides a model for the reduced hapticity species.
ICHEC Project:Estimating the potential energy surfaces around pi-coordinated arene ligands in (eta-Arene)Cr(CO)3 complexes
Publication:J. Phys. Chem. A, 2011, 115 (14), pp 2985–2993
URL: http://pubs.acs.org/doi/abs/10.1021/jp112168u
Status: Published

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